ENTOMOSTRACA OF MINNESOTA. 115 



dimorphic states are very distinct and seem, in part at least, to be 

 governed by habitat. The colors are frequently brilliant, varying 

 from deep indigo to greenish brown. The coloring matter is some, 

 what irregularly distributed but is most persistent between the bases 

 of the feet, in the last segment of the abdomen and in the last joints 

 of the antenuce. 



The full-grown female measures about 0.70 mm., the males being 

 more slender. Oviferous females often have the fourth pair of feet 

 with two-jointed rami. American authors find the species pelagic, 

 and Brady, though he found it in ditches immediately connected with 

 large sheets of water. 



Marsh notes that there is a resemblance between this species and 

 C. pentagonus Vosseler. 



Cyclops capillatiis Sars. 



"Cephalothorax sub ovate; anteriorly uniformly rounded; seg- 

 ments projecting somewhat laterally, the last being scarcely wider 

 than the first abdominal segment. Abdomen attenuated posteriorly; 

 caudal rami almost as long as the last three abdominal segments, 

 hardly divergent; the external and internal apical sette short and 

 nearly equal, the interior of the median setae as long as the abdomen, 

 lateral seta about in the middle of the stylet. Anteunte of the first 

 pair robust, slightly exceeding the first segment of the body when re- 

 flexed, with the twelve joints densely covered with long and divergent 

 hairs. The last joint of the outer rami of swimmiag feet are elongated 

 and armed externally with three spines, internally with four setse; the 

 interior apical spine of the interior rami of the fourth pair of feet 

 longer than the exterior. Feet of the fifth pair large, with a large 

 and thick basal segment and a small oval second joint bearing one 

 long seta and a short spine. Ovisacs small, narrow and divergent. 

 Eye very small. Length nearly 2.0 mm." 



Very close to G. viridis in many points. Found only in Scan- 

 dinavia. 



Cyclops crassicaudis Sars. 



Cephalothorax elongate- ovate; segments produced laterally, espe- 

 cially the last, which extends into a somewhat procurved process. 

 Abdomen short and thick, first segment somewhat excavated; caudal 

 rami equaling the last two segments of the abdomen. External 

 apical seta longer than the internal, both short; median set?e long. 

 Antennte of the first pair 12-jointed, scarcely longer than the first 

 segment. Swimming feet short and thick, spines and setse short; the 

 interior apical spine of the last joint of the inner ramus of the fourth 



